Copper

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Mineral guide

Learn about Copper

native copper with spinel-twinned crystals and arborescences; notable from Lake Superior, Itauz, Dongchuan, Corocoro, prized for color and localities.

Regional guide

Copper from Keweenaw Peninsula, Michigan, USA

The Keweenaw Peninsula is the classic native-copper locality: a place where copper was not merely an ore mineral locked in sulfides, but the metal itself—dense, malleable, and often sculptural—precipitated as copper, Cu, in billion-year-old volcanic rocks. For collectors, “Keweenaw copper” is a category unto itself. It can appear as wiry arborescent sprays, thick hackly sheets, crystal groups with sharp metallic faces, rounded glacial float nuggets, massive vein copper, copper-filled amygdules in basalt, and copper in conglomerate where the metal laces between volcanic pebbles.